In IOT (Internet of Thing) and many other location related applications, It is required that an infrastructure be able to estimate the position of one or several wireless objects or target nodes. It is still a great challenge to achieve accurate location estimation in a wireless environment at low cost. This invention is to present a simple method to achieve a robust location estimation with good accuracy at low cost.
In a typical location estimation system, there are several reference nodes, or gateways, whose locations are known, and one or several target nodes or motes, whose locations are to be estimated. In order to estimate the location of the target node, some metrics characterising the positioning information of the target node against the reference nodes, such as the distance or angles, needs to be measured through either the radio transmission by the target node and received by the reference nodes, or the other way around. In this invention, we consider the case where the target node makes radio transmission, which is received by the gateways (reference nodes) around it.
The following description describes examples of the invention in which the position of the mobile node is determined in a 2-dimensional plane. Albeit important, this application is not limiting and the invention includes as well variants in which the mobile nodes are localised in a 3-dimensional space.